W3LPL's forecast for upcoming Solar Cycle 25 - Apr 2021

Frank Donovan, W3LPL is one of the top contesters in the USA and is a key forecaster of upcoming conditions on the HF amateur radio bands.

In a recent forecast (April 2021), he made a forecast about how good upcoming Solar Cycle 25 would be based on the Solar Flux numbers at the end of December 2021. I have put together a graphic which shows this above. The starting point for April 2021 is a solar flux index of 77 which is roughly the average for the month.

W3LPL wrote... “If the SFI persists below 90 through December 2021, then propagation should improve gradually until a solar maximum weaker than Cycle 24’s arrives in 2024.

If the SFI persists above 110 through December 2021, then propagation should improve rapidly until a solar maximum similar to Cycle 24’s arrives in 2024.

“If the SFI persists above 125 through December 2021, then propagation is likely to improve more rapidly until a solar maximum stronger than Cycle 24’s arrives in 2024.”

(SFI = Solar Flux Index)

As with everything on the sun, there is always an amount of uncertainty in solar forecasts but it will be interesting to revisit this at the end of the year and see where we're at.

Link...
1) K7RA Solar Update - 23rd April 2021

Latest forecast for the next Solar Cycle - Dec 2019

An international panel of scientists co-chaired by NOAA and NASA release reports every few months on the state of the sunspot cycle. This is probably the most accurate source in terms of what is likely to happen.

Back in April of 2019, the previous report predicted that the  solar minimum would likely happen between July 2019 and September 2020. In the most recent report dated December 2019, they are predicting that the minimum has been pushed back. They predict that it will now occur sometime between November 2019 and October 2020.

As for the upcoming Solar Cycle 25, they are still predicting that it will be similar in intensity to the last solar cycle with a smoothed sunspot number (SSN) of 115. The peak is predicted to occur between November 2024 and March 2026.

Original press release...
SOLAR CYCLE 25 FORECAST UPDATE published: Monday, December 09, 2019 22:30 UTC The NOAA/NASA co-chaired, international panel to forecast Solar Cycle 25 released their latest forecast for Solar Cycle 25. The forecast consensus: a peak in July, 2025 (+/- 8 months), with a smoothed sunspot number (SSN) of 115. The panel agreed that Cycle 25 will be average in intensity and similar to Cycle 24. Additionally, the panel concurred that solar minimum between Cycles 24 and 25 will occur in April, 2020 (+/- 6 months). If the solar minimum prediction is correct, this would make Solar Cycle 24 the 7th longest on record (11.4 years).

New Prediction for Sunspot Cycle 24...

Reading through some recent e-mails, I came accross this...

NASA Releases New Predictions for Solar Cycle 24......An international panel of experts -- led by the National Oceanic andAtmospheric Administration (NOAA) and sponsored by NASA -- has released a new prediction for the next solar cycle: Solar Cycle 24 will peak in May 2013 with a below-average number of sunspots. "If our prediction is correct, Solar Cycle 24 will have a peak sunspot number of 90, the lowest of any cycle since 1928 when Solar Cycle 16 peaked at 78,". This report clarifies a NOAA report from earlier this month that stated that Solar Cycle 24 would bring "90 sunspots per day on average."

Looking at the date, they are predicting the peak to be between 80 and 100 sunspots per month at the peak. So what does this mean? Let's compare it to previous cycles...

It looks as if it will be similiar but slightly lower than the peak of 1968/9 but worse than the last 3 peaks. What does this mean in practical terms?

In reality, near the sunspot maximum, the HF bands (14 MHz to 28 MHz) will be hopping and there will be worldwide dx regardless of how bad it turns out to be. The big issue is what will propogation on 50 MHz be like?

I remember reading before that the peak of 1968 was supposed to be pretty poor for DX on 6 metres with slim pickings via F2. If it turns out as predicted, I'd expect that there will be plenty of F2 type openings North-South from say Europe to Africa and South America. The big problem is will the MUF get high enough to support East-West type openings from say Europe to North America?....or Europe to the Far East? Stations in Southern Europe will probably work loads (EA/CT/I/etc) but what about those above 50 deg North?